In high pressure fluid pumps having reciprocating plungers, it is necessary to provide a seal around the plunger to prevent the leakage of high pressure fluid. In such pumps, the seal must be able to operate in a high pressure environment, withstanding pressures in excess of 10,000 psi, and even up to and beyond 50,000-70,000 psi.
Currently available seal designs for use in such an environment include an extrusion resistant seal that seals against the plunger and is supported by a back-up ring. The back-up ring and seal may be supported by a seal carrier and may be biased toward the seal carrier with a coil spring that encircles the plunger. The spring may be held in place against the seal with a collar that has a bore through which the plunger passes and that has a flange encircling one end of the spring.
One problem with current seal designs is that the tolerances for clearance between the plunger and the back-up ring may be very difficult to achieve and maintain. Very typically, therefore, the plunger and the back-up ring come into contact, generating frictional heating, which in turn may cause the seal to fail. Another problem with current seal designs is that components of the seal may wear over time, causing fluid to leak around the plunger.